Process of improving regenerated cellulose



Patented Aug. 1, 1939 "PATENT OFFICE PROCESS OF IMPROVING REGENERATED' CELLULOSE Fritz Siefert, Ludwigshafen-on-the-Rhine, Ger

many,

assignor to I. G. Farbenindustrie Ak tiengesellschaft, Frankfort-on-the-Main, Ger

many

No Drawing. Application September 29, 1938, Serial No. 232,287. In Germany November 12,

6 Claims.

The present invention relates to a new process of improving regenerated cellulose.

I have found that a regenerated (dissolved and precipitated) cellulose can be improved in an excellent manner by treating it with formaldehyde solutions in the presence of sulphocarboxylic (sulphonic carboxylic) acids and subjecting it to a drying process. There may be mentioned for example aliphatic and aromatic sulphocarboxylic acids, such as sulpho-acetic acid, sulpho-palmitic acid, sulpho-benzoic acid, sulpho-phthalic acid and sulpho-salicylic acid. Even small amounts of the sulpho-carboxylic acids, probably acting catalytically, are usually sufficient, as for example from 2 to 5 grams per liter of treatment bath. The formaldehyde solutions may advantageously be dilute, as for example from 2.5 to 5 per cent. It is preferable to carry out the subsequent drying at elevated temperature, as for example at from 80 to 100 C.

By the said treatment, the regenerated cellulose, as for example artificial silk or cell-wool, is improved in various respects. In particular, after the said treatment, they no longer have, or

- only have to a greatly reduced degree, the objectionable properties due to swelling phenomena, as for example strong creasing, reduced tensile strength in the moist state which leads to rapid wear, strong absorption of water in rain, formation of water spots, considerable loss of substance during mercerization and the like. The treatment does not result in any weakening of the cellulose fibre such as takes place by treatment with formaldehyde in the presence of strong inorganic acids and their salts.

To the bath serving for the treatment there may also be added other substances, such as softening agents and hydrophobing agents, as for example those which in the treatment of cellwool cables open the cable.

The following examples will further illustrate the nature of this invention but the invention is not restricted to these examples.

Example 1 A cable of cell-wool is led, before the final drying, through a 2.5 per cent formaldehyde solution containing 0.5 per cent of sulpho-salicylic acid and 0.2 per cent of the product obtainable by the reaction of 1 molecular proportion of triethanolamine monostearic acid ester with 2 mo lecular proportions of ethylene oxide (as a cableopening agent). After cutting the fibres and drying at 100 C. there is obtained a staple fibre which by reason of its elasticity and small absorptive power for water is extraordinarily well suited for working up together with Wool; mixed yarns or mixed fabrics of wool and the staple fibre treated in the said manner scarcely differ from pure wool.

If the staple fibre obtained in the said manner be spun with cotton, the yarns or fabrics prepared from the mixed fibres may be mercerized in the usual way without injury to the staple fibre component.

Example 2 An artificial silk fabric is treated for one quarter of an hour at ordinary temperature in a washing machine or in a jigger with a 2.5 per cent solution of formaldehyde which contains 0.3 per cent of ortho-sulpho-benzoic acid. After squeezing, the strip of fabric is led over a drying cylinder heated to 100 C. or through a drying chamber heated to the same temperature, whereby the drying requires from half to one hour depending on the thickness of the material.

A material is obtained which, without showing external change, has excellent resistance to creasing, shows no Water spots when wetted, does not shrink and, because it is not capable of swelling, has an excellent resistance to moisture.

What I claim is:

1. The process of improving regenerated cellulose, which comprises treating it with a formaldehyde solution in the presence of an aromatic sulphocarboxylic acid and subjecting it to a drying process.

2. The process of improving regenerated cellulose, which comprises treating it with a formaldehyde solution in the presence of sulpho-salicylic acid and subjecting it to a drying process.

3. The process of improving regenerated cellulose, which comprises treating it will a formaldehyde solution in the presence of ortho-sulphobenzoic acid and subjecting it to a drying process.

4. Improved regenerated cellulose being free from undesirable swelling properties and possessing good tensile strength in the moist state, comprising a product resulting from the reaction of regenerated cellulose with a formaldehyde solution in the presence of an aromatic sulphocarboxylic acid, and subjecting the resulting product to a drying process.

5. Improved regenerated cellulose being free from undesirable swelling properties and possessing good tensile strength in the moist state, comprising a product resulting from the reaction of regenerated cellulose with 9, formaldehyde solution in the presence of sulpho-salicylic acid, and subjecting the resulting product to a. drying process.

6. Improved regenerated cellulose being free frim undesirable swelling properties and possessing good tensile strength in the moist state, corn-- prising a. product resulting from the reaction of regenerated cellulose with a formaldehyde solution in the presence of ortho-sulpho-be'nzoic acid, and subjecting the resulting product to a. drying process; I

FRITZ SIEFERT. 

